The present invention relates to a liquid crystal display device and, more specifically, to an active matrix type liquid crystal display device of a thin film transistor (TFT) type or the like and a manufacturing method for the same.
Two types of liquid crystal display devices are mainly used: one is a so-called vertical electric field type in which electrodes are disposed on the liquid-crystal-layer side of each of two substrates disposed in opposition to each other with a liquid crystal layer interposed therebetween; and the other is a lateral electric field type (in-plane-switching mode: IPS mode) in which lateral electric fields having components parallel to upper and lower substrates are applied to a liquid crystal gap therebetween. In either type, alignment films for controlling the initial alignment of liquid crystal molecules are respectively formed on the surfaces of the mutually opposed substrates that are closest to a liquid crystal layer, and the liquid crystal layer is sealed on four sides by a sealing material.
An area in which the sealing material is formed is called a peripheral area or a peripheral portion in contrast with an effective display area in which pixels are formed, and lines are led to a terminal portion through a layer underlying the sealing material on at least one side of the peripheral portion.
Japanese Patent Laid-Open Nos. 133787/2001 and 264793/2001 are publicly known as examples of the cross-sectional structure of the above-described peripheral portion.
The peripheral portion has two important roles, one of which is to fix upper and lower substrates with a sealing material, and the other of which is to lead lines. The former has the problem that its strength needs to be increased, and it is particularly important to increase the adhesion force between the sealing material and a layer to which the sealing material adheres. The latter has the problem that reliability needs to be ensured in a lead portion of each line, and it is particularly important to prevent the lead portion from coming into direct contact with a sealing portion. Therefore, the invention aims to provide a liquid crystal display device in which the two problems can be compatibly solved.
In addition, a liquid crystal display device in which an organic insulating film is constructed in a layer overlying lines and electrodes are constructed on the organic insulating film is disclosed in, for example, Japanese Patent Laid-Open No. 230378/1997. However, the present inventor has found out a new problem that in the case where an organic insulating film and a sealing material are stuck to each other, a layer to which to stick the sealing material is stuck is the organic insulating film itself, and in this case, the adhesion force therebetween lowers. Therefore, the invention also aims to provide a liquid crystal display device in which the above-described two problems can be compatibly solved even if the liquid crystal display device has an organic film layer formed in contact with an alignment layer in each pixel.
Further problems to be solved by and further objects to be achieved by the present application will become apparent in the present specification.
Representative examples for solving the problems according to the invention will be described below.
(1)
A liquid crystal display device includes a liquid crystal layer and a color filter layer interposed between a first substrate and a second substrate, a plurality of gate lines formed on the first substrate, a plurality of drain lines disposed on the first substrate in matrix form to intersect the plurality of gate lines, thin film transistors formed on the first substrate and respectively disposed to correspond to intersections of the gate lines and the drain lines, a sealing material which causes the first substrate and the second substrate to adhere to each other along their peripheral portions, and alignment films formed on at least surfaces of the respective first and second substrates, which surfaces are closest to the liquid crystal layer. The first substrate has an organic film formed between each of the thin film transistors and the alignment film formed on the first substrate, and the organic film is removed in an area of the sealing material. The sealing material is adhered to an inorganic film on the first substrate and to an organic film on the second substrate.
(2)
In a liquid crystal display device as in (1), a protective film of each of the thin film transistors is a stacked film made of an inorganic film formed of SiN and a photosensitive organic material, and the stacked film made of the inorganic film and the photosensitive organic film has openings worked through one exposure cycle during formation of contact holes.
(3)
An active matrix type liquid crystal display device includes a liquid crystal layer and a color filter layer interposed between a first substrate and a second substrate, a plurality of gate lines formed on the first substrate, a plurality of drain lines disposed on the first substrate in matrix form to intersect the plurality of gate lines, thin film transistors formed on the first substrate and respectively disposed to correspond to intersections of the gate lines and the drain lines, and a sealing material which causes the first substrate and the second substrate to adhere to each other along their peripheral portions. Each of the drain lines is connected to a metal material formed in the same process as the gate lines on a display-area side of the sealing material, is led under the sealing material as a metal material layer formed in the same process as the gate lines, and in an external-connection-terminal-side area outside the sealing material, is led from the metal material layer formed in the same process as the gate lines and is connected to an external connection terminal via a metal material layer formed in the same process as the drain lines.
(4)
In a liquid crystal display device as in (3), an organic film formed as a protective film for the thin film transistor has an opening in an area under the sealing material in which each of the drain lines is led as the metal material layer formed in the same process as the gate lines, and the sealing material in the area is adhered to an inorganic insulating film.
(5)
In a liquid crystal display device as in (3) or (4), a protective film for the thin film transistor is a stacked film made of an inorganic film formed of SiN and a photosensitive organic material, and the stacked film made of the inorganic film and the photosensitive organic film has openings worked through one exposure cycle during formation of contact holes.
(6)
A liquid crystal display device includes a liquid crystal layer and a color filter layer interposed between a first substrate and a second substrate, a plurality of gate lines formed on the first substrate, a plurality of drain lines disposed on the first substrate in matrix form to intersect the plurality of gate lines, thin film transistors formed on the first substrate and respectively disposed to correspond to intersections of the gate lines and the drain lines, alignment films formed on at least surfaces of the respective first and second substrates, which surfaces are closest to the liquid crystal layer, polarizers respectively disposed on surfaces of the first substrate and the second substrate on sides opposite to the liquid crystal layer, and a sealing material which causes the first substrate and the second substrate to adhere to each other along their peripheral portions. Each pixel in a pixel area defined as an aggregation of pixels has a pixel electrode and a common electrode on the first substrate and the liquid crystal layer is driven by an electric field being generated between the pixel electrode and the common electrode and having a component parallel to the first substrate. A transparent electrode wider than at least each of the pixels is formed in an area between the pixel area and the sealing material on the first substrate. The respective alignment films have areas formed on the first substrate and the second substrate and positioned in an area in which the transparent electrode is formed, and the respective polarizers have areas positioned and provided in the area in which the alignment films are formed. The polarizers, the liquid crystal layer and the alignment films are arranged to realize a normally black mode.
(7)
A liquid crystal display device includes a liquid crystal layer and a color filter layer interposed between a first substrate and a second substrate, a plurality of gate lines formed on the first substrate, a plurality of drain lines disposed on the first substrate in matrix form to intersect the plurality of gate lines, thin film transistors formed on the first substrate and respectively disposed to correspond to intersections of the gate lines and the drain lines, a sealing material which causes the first substrate and the second substrate to adhere to each other along their peripheral portions, and column-shaped spacers which determine a gap between the first substrate and the second substrate. Each of the column-shaped spacers has at least two areas having different thicknesses in an area between a pixel area defined as an aggregation of pixels and the sealing material. At least one of the at least two areas has a height which determines the gap between the first substrate and the second substrate, while another of the at least two areas is formed to be thinner than the at least one. The column-shaped spacers are made of a material which exhibits a light shielding effect.
(8)
A liquid crystal display device includes a liquid crystal layer and a color filter layer interposed between a first substrate and a second substrate, a plurality of gate lines formed on the first substrate, a plurality of drain lines disposed on the first substrate in matrix form to intersect the plurality of gate lines, thin film transistors formed on the first substrate and respectively disposed to correspond to intersections of the gate lines and the drain lines, and a sealing material which causes the first substrate and the second substrate to adhere to each other along their peripheral portions. The color filter layer is formed on the first substrate and has a line superposition area in which a material of each of the drain lines and a material of each of the gate lines are formed with the end portions of the respective materials superposed on each other with an interlayer insulting film interposed therebetween in a portion between a pixel area defined as an aggregation of pixels and a terminal area, and at least one layer of the color filter layer is formed in the line superposition area.
(9)
A liquid crystal display device includes a liquid crystal layer and a color filter layer interposed between a first substrate and a second substrate, a plurality of gate lines formed on the first substrate, a plurality of drain lines disposed on the first substrate in matrix form to intersect the plurality of gate lines, thin film transistors formed on the first substrate and respectively disposed to correspond to intersections of the gate lines and the drain lines, and a sealing material which causes the first substrate and the second substrate to adhere to each other along their peripheral portions. The sealing material is adhered to an organic material of the first substrate and to an inorganic material of the second substrate.
(10)
A liquid crystal display device as in (9), the inorganic material of the second substrate to which the sealing material is adhered is the second substrate itself.
Further aspects and features of the invention will become apparent from the following description of embodiments of the invention.